The invention is related to the field of ice adhesion, specifically, to decreasing the adhesion strength of ice to surfaces of solid objects, in particular, to land-based surfaces in transportation systems.
Statement of the Problem
Ice adhesion to certain surfaces causes various types of problems. For example, excessive ice accumulation on aircraft wings endangers the plane and its passengers. Ice on ship hulls creates navigational difficulties, expenditure of additional power to navigate through water and ice, and unsafe conditions. Problems associated with ice are particularly obvious with respect to land-based surfaces in transportation systems, including roads and highways, bridges, parking lots, sidewalks, airport runways, train tracks. Ice on roads and bridges is frequently a cause of automobile accidents resulting in personal injury and death, as well as material damage. Large amounts of material resources, money and man-hours are spent annually to remove ice and snow from roads other transportation-related surfaces to clear them for use and to reduce risks of slipping and skidding on iced surfaces. The accidents and time delays associated with iced surfaces are major causes of inconvenience and personal and economic damage.
The invention helps to solve some of the problems mentioned above by providing systems and methods for modifying the adhesion strength of ice to surfaces of solids. Systems and methods in accordance with the invention are particularly applicable to problems associated with ice and surfaces in the field of transportation. Nevertheless, systems and methods in accordance with the invention are generally applicable to reduce problems caused by ice.
A basic embodiment for deicing a surface of a solid object includes a first electrode contiguous with the surface, and a second electrode. The first and second electrodes are separated by an interelectrode distance, and they cover the surface being protected against ice. The first electrode and the second electrode define an interelectrode space between the electrodes. A power source is connected to the first electrode and the second electrode. The power source is a DC power source or a low-frequency AC power source. When conductive water fills the interelectrode space between the electrodes, the water completes an electrical circuit including the two electrodes. A DC or low-frequency AC current is applied, causing electrolysis of the water molecules and formation of gas bubbles that reduce ice adhesion. Water in the electrode space providing electrical connection between the electrodes may be ice or liquid water. The interelectrode distance typically does not exceed 10 mm. Preferably, the interelectrode distance has a value in a range of about from 0.5 to 10 mm. The power source is typically capable of providing a voltage in a range of about from 2 to 100 volts. The current density in the water in the interelectrode space at the electrodes has a value in a range of about from 0.1 to 10 mA/cm2.
In some embodiments in accordance with the invention, the surface of the object being protected is electrically nonconductive. A typical example is the nonconductive surface of a concrete or asphalt road. In certain of these embodiments, the first electrode is a continuous layer of conductive material contiguous with and covering a first portion of the surface, the second electrode is a continuous layer of conductive material contiguous with and covering a second portion of the surface, and the interelectrode space covers a third portion of the surface between the first and second portions. The conductive material may be selected from many compositions and structures of conductive materials, including metal sheets, conductive metal oxide, conductive concrete, conductive asphalt, conductive polymer, carbon, and conductive paint.
In other embodiments in which the surface is electrically nonconductive, the first electrode is a bottom electrode layer disposed on the surface, and the second electrode is a porous top electrode layer located above the first electrode. Such embodiments typically include a porous insulator disposed between the bottom first electrode and the porous top second electrode layer. Thus, certain embodiments include a laminate coating covering the surface of the object, whereby the laminate coating comprises a bottom electrode layer, a porous insulator layer, and a porous top electrode layer.
In other embodiments, a composite mesh coating covers the nonconductive surface. Typically, a composite mesh coating contains a plurality of first electrode wires, a plurality of second electrode wires, and a plurality of insulator fibers, wherein the insulator fibers are woven into the mesh to insulate electrically the first electrode wires from the second electrode wires.
In a second group of embodiments in accordance with the invention, the surface of the object being protected against icing is conductive and serves as the first electrode. In these embodiments, the second electrode is a porous conductive layer located above the first electrode surface. Such embodiments typically further include a porous insulator layer that electrically insulates the second electrode from the first electrode surface. For example, some embodiments include a mesh that covers the first electrode surface. Such a mesh typically comprises conductive second electrode wires having a top and bottom, and the bottom of the second electrode wires is coated with a coating of an electrical insulator. The mesh is structured and assembled in the system so that the second electrode wires are separated from the first electrode surface by an interelectrode distance in accordance with the invention. The mesh may be mounted proximate to the first electrode surface using one of various techniques. For example, the mesh may be pressed onto the first electrode surface such that the bottom of the second electrode wires is not in electrical contact with the first electrode surface. In another basic embodiment, a composite mesh coating covers the first electrode surface and the composite mesh coating comprises a plurality of electrically conductive second electrode wires and a plurality of electrically insulating insulator fibers. The mesh is constructed such that the insulator fibers separate the second electrode wires from the first electrode surface.
Numerous other structures and compositions in accordance with the invention may be utilized.